Resistance welding devices are used for welding various components, and in particular, for spot welding in body construction. Typically, two or more sheets to be welded together are brought into contact with each other and the welding electrodes are pressed against the surfaces of these sheets by the welding guns. The welding current melts the contact zone between these sheets to create a spot weld.
The curve of the welding current must be controlled and/or regulated within narrow limits so that the spot weld has the necessary quality and the sheets to be welded are joined properly and without the occurrence of spatter.
Various methods can be used for optimum regulation of the welding current curve. In a static control method, the welding time, strength of the welding current, and the force of the electrode pressure are fixed. More complex and expensive dynamic regulating methods utilize reference curves of the dynamic welding current and of the dynamic electrode voltage drop. In these methods, during welding, measuring devices continuously measure the dynamic welding current and the electrode voltage. If any deviations from the reference curve occur, the control and/or regulating devices adjust the welding current source so that the measured current and voltage curves match the specified reference curve as closely as possible. Alternatively, other physical parameters may be used for welding regulation, for example ultrasonic signals conducted into the weld or noise signals produced by the welding process, electrode force, electrode movement, thermovoltages, power, resistance, and energy.
In all known control and/or regulating methods, the control and/or regulating parameters (also referred to herein as the reference data sets) depend upon the welding guns used in each case. Depending on the size of the guns, the pressure generated by the guns, and the various shapes of the welding electrodes in the guns, these control and/or regulating parameters may change markedly.
In an industrial manufacturing device, a large number of welding guns may be used. Frequently, 250 or more welding guns will be connected via quick-change couplings to the various welding current sources. In order for the welding performed with a given set of welding guns to proceed optimally, the data set with the specific control and regulating parameters associated with those welding guns must be loaded into the program memory of the control and/or regulating device of the welding device every time the guns are changed. The control and regulating parameters are then stored in a central memory integrated either into the control and/or regulating device, or in the case of several welding stations, within a manufacturing system, connected by a data network with the various control and/or regulating devices. The persons operating the welding devices must be careful to be sure that the control and regulating data sets corresponding to the welding guns being used are properly loaded before welding.